Device for varying the quantity of working medium in hot-gas reciprocating engines



Nov. 4, 1952 E. J. J. VELDHUYZEN 2,616,244

DEVICE FOR VARYING THE QUANTITY OF WORKING MEDIUM IN HOT-GASRECIPROCATING ENGINES Filed June 21, 1949 501/020 J mv Jamal/5 Mflm/YZEN.

J- a gn z Patented Nov. 4, 1952 DEVICE FOR VARYING THE QUANTITY OFWORKING MEDIUM IN HOT-GAS RECIP- ROCATING ENGINES Eduard Johan JacobusVeldhuyzen, Amsterdam, Netherlands, assignor to Hartford National Bankand Trust Company, Hartford, Conn., as

trustee Application June 21, 1949, Serial No. 100,380

In the Netherlands July 2, 1948 2 Claims.

This invention relates to hot-gas reciprocating I engines (whichexpression is to be understood to include refrigerating machinesoperating according to the reversed hot-gas engine principle) comprisinga device for varying the quantity of working medium taking part in thecycle.

It is known to vary the quantity of working medium in a hot-gasreciprocating engine in order to vary the power absorbed or delivered bythe engine at the instant at which the medium partaking in thethermo-dynamic cycle substantially attains the lowest pressure during arevolution. This method of control exhibits the disadvantage of beingunsuitable for rapid control of this engine, which is disadvantageous,.for example with traction engines and engines driving generators.

If the power is required to be increased by supplying working medium,the medium added has a retarding effect on the working piston in thiscontrol method. At first, the work done in compressing the medium in onecycle exceeds the work done in compressing the medium in the precedingcycle and thus is greater in relation to the energy made available onexpansion of the medium in the preceding cycle. Due to this, the powerdelivered by the machine is at first lower instead of higher and theengine tends to slow down. A similar phenomenon occurs, if the power isrequired to be reduced by decreasing the quantity of working medium. Inthis case, the work done in compressing the medium in one cycle is, atfirst, less than the work done in compressing the medium in thepreceding cycle and thus is less in relation to the energy madeavailable on expansion of the medium in the preceding cycle, so that atfirst the engine delivers a higher power instead of a lower power andtends to accelerate.

In effecting such control at the instant of substantially the lowestpressure occurring during the cycle, the range of variation of the poweris comparatively small, since it is determined by the maximumpermissible minimum pressure and the lowest attainable minimum pressure,for example, 1 atm. In this event, a variation of, say, 1 to 12 ispossible, if the highest permissible minimum pressure is 12 atm.Moreover, it is difilcult to stop the engine at the lowest attainableminimumpressure, since, for example, the power delivered is stillcomparatively high with respect to frictional losses. Anotherdisadvantage is that the means for control at the lowest pressure cannotserve simultaneously for driving the engine, owing to the supply ofcompressed air in this position of the piston and displacer, no positivework is performed by which the piston and displacer would be actuated.Consequently, an additional starting device is required.

The object of the invention is to provide an alternative construction ofhot-gas reciprocating engine in which these difficulties are avoided.

According to the invention, a hot-gas reciprocating engine having adevice for varying the quantity of working medium taking part in thecycle, is characterized in that it comprises means by which the workingspace of the engine, both at the instant of supplying working medium andat the instant of carrying off working medium, can be made tocommunicate periodically with a second chamber containing Workingmedium,

in that position of the piston and displacer in which the medium takingpart in the thermodynamic cycle has attained substantially the highestpressure occurring during the cycle.

This control method is very suitable for traction engines and forengines driving generators. If the quantity of medium is increased atsubstantially the highest pressure occurring during the cycle, thehighest pressure of the medium increases, so that the medium addedimmediately partakes in the expansion phase of the cycle.

The energy made available on expansion of the medium in a cycleinitially exceeds the energy made available on expansion in thepreceding cycle and thus is greater in relation to the work done incompressing the medium in the preceding cycle, due to which the engineimmediately delivers a higher power. Upon reducing the quantity ofmedium, the highest pressure of the medium taking part in the cycledecreases, with the result that a quantity of medium is carried off anddoes not partake in the subsequent expansion, so that the energy madeavailable on expansion of the medium in a cycle is initially less thanthe energy made available on expansion in the preceding cycle and thusis smaller in relation to the work done in compressing the medium in thepreceding cycle.

In this method of control it is possible to vary the power to a muchhigher degree, since the range of variation is determined by the highestpermissible maximum pressure and the lowest attainable maximum pressureoccurring during a cycle, for example 1 atm. Owing to this, a variationof, say, 1 to 30 is possible, if the highest maximum pressure is 30 atm.Moreover, the engine can be stopped if the maximum pressure becomesequal to atmospheric pressure, since, for example, the power thendelivered is comparatively low with respect to frictional losses. Inaddition, starting the engine with the use of compressed air in thecorrect positions of the piston and the displacer. if required afterturning, will be possible by the same means which serve for controllingthe power output, since in these positions of the piston and thedisplacer positive work is delivered, by which the piston and thedisplacer are actuated. In this event, the provision of a separatestarting device is not necessary.

In order that the invention may be more clearly understood and readilycarried into effect, it will now be described more fully with referenceto the accompanying diagrammatic drawing which represents, by Way ofexample, a hot-gas reciprocat ing engine according thereto.

Fig. 1 is a view partly in crosssection of a hot-gas engine employingapplicants invention;

piston 1 and a displacer 2,-which determine the" space in which thecycle takes place, which space comprises a cold chamber 3 and a hotchamber 4. The cold chamber 3 is connected with the hot chamber 4 by wayof a cooler 5, a regenerator t and a heater 7. Both the piston l and thedisplacer 2 are connected, by connecting rods, to a crank-shaft 8. Thecrank associated with the piston I and the crank associated with thedisplacer 2 may be arranged at an angle of 90 to one another.

A channel H contains a control valve 9 which is kept closed by means ofa spring I0. Through the channel H, the cold chamber 3 may be made tocommunicate with a control chamber I2 in which a desired pressure can bemaintained.

When it is desired to start the engine, either the control chamber IE ora separate starting vessel l3 may be used, which vessel may be connectedwith the working space of the engine through channel H by way of a cockI4, a cock l5 controlling the connection between the working space andthe chamber 12 then being closed.

The valve 9 can be opened by means of a lever l6, a lifting rod I1 and acam l8. Fig. la is a 4 side view of this cam. The shape of the cam I8 issuch that the valve 9 opens when the pressure of the working mediumtaking part in the cycle substantially attains its highest value;

It is clear that, besides in the manner illustrated in the drawing, theinvention may be carried out in many other ways, for instance by meansof slides and cooks, without departing from its scope.

What I claim is:

l. A hot-gas reciprocating engine comprising a working space, acrankshaft, a piston connected thereto reciprocating in said workingspace, a chamber containing Working medium at a variable predeterminedpressure, conduit means connecting said chamber to said working spaceand valve means interposed in said conduit means and actuated by saidcrankshaft to open said valve means at the point of highest pressure inthe cycle in order to supply or carry ofi' working medium to or fromsaid Working space.

2. A hot-gas reciprocating engine comprising a working space. acrankshaft, a piston connected thereto reciprocating in said workingspace, a chamber containing Working medium at predetermined pressure,conduit means connecting said chamber to said working space to supply orcarry off working fluid to 'or from said working space, valve meansinterposed in said conduit means to control the flow therethrough,resilient means to normally close said valve means, cam means driven bysaid crankshaft to open said valve means at the point of highestpressure in the cycle.

EDUARD JOHAN JACOBUS VELDHUYZEN.

REFERENCES CITED The following references are of record in the file ofthis patent.

UNITED STATES PATENTS Number Name Date 826,313 Clark July 17, 1906FOREIGN PATENTS Number Country Date 2,999 Great Britain Dec. 7, 18601,784 Great Britain Apr. 14, 1882

